My take is that as etaco suggests, O’Reilly will not give Obama a hard time whatsoever. He’ll find a place where he thinks he won’t be accused of having been a walkover, but where “middle of the road” people will (in his mind) be saying “Ooooo, wasn’t O’Reilly fair!”
Just as he did with Hillary, of whom he asked not a single tough question.
Example tough but entirely reasonable question he could and should have asked Hillary:
"You claim frequently that your husband created millions of jobs and ‘grew the economy’ and promise that you will do the same. But you’ve never named any specific action of the former President that created jobs or grew the economy.
He raised taxes, of course, but that slows economic growth and job growth. He increased regulation, but that also slows economic and job growth.
Spending and the deficit were put under better control, but that was the Republican-controlled Congress, and in any case you’re not proposing to decrease total spending. So what did he do that created jobs and grew the economy?"
Oh, that would have been priceless. She would have had nothing to say. Could have had nothing to say.
And when she can’t name what it was that her husband did to create jobs and grow the economy, then what does she mean saying she’s going to do the same thing?
But of course O’Reilly did not do this, or any such thing. Instead, he expounded on his own fascist views regarding the oil companies and blamed energy problems on both political parties equally, taking up (seemingly) most of the interview with his own diatribes having nothing to do with Mrs Clinton.
IMO, Bill O’Reilly is all about Bill O’Reilly and what he thinks will play popularly with what he sees as his core audience, and chooses his content and I think in some cases his opinions based on that. A complete demagogue. I am pretty sure he will think it serves Bill O’Reilly best to be a “surprisingly” pleasant interview for Obama.
Besides that, he is probably under orders from ownership to play this interview to a DNC-pleasing level of softness, as personal opinion.
By the way, did you know that O’Reilly admits to being mendacious? I e-mailed him to let him know that he doesn’t know what the word means (he seems to think it means pugnacious) and before using it again in his vocabulary-showoff part of the show,
he needed to find out, but I suppose his staffer feared to correct O’Reilly or if O’Reilly was presented with the information, he was too arrogant to accept he could be wrong, so he has continued misusing the word.
Anyway, by his own statement (though actually the situation is that he doesn’t know what he’s saying) as well as being an un-admitted demagogue he’s an admitted liar 
